One exemplary cause of vehicle vibrations at both high and low traveling speeds corresponds to force variations at respective tire spindle locations. This phenomenon is typically referred to as tire uniformity. Tire high speed uniformity (HSU) may be of particular interest as related to tire performance levels, since potential non-uniformity characteristics of a tire can produce a significantly greater amount of vibration at faster highway road speeds, such as those in excess of 25 mph.
High speed uniformity (HSU) has become a growing concern in the automobile industry, and thus many tire manufacturers are being pressured to implement HSU control. Tire HSU measurement, however, has been difficult and quite costly, making HSU industrial control very difficult.
A multitude of various tire parameters have conventionally been identified and measured in an effort to predict and control these force variations and any resultant undesirable levels of vibration. In accordance with aspects of the present invention, it is desired to combine multiple tire parameter measurements to predict or determine tire uniformity, including the radial and tangential force variations at both low and high speeds.
One known attempt at predicting tire HSU is disclosed in U.S. Pat. No. 5,396,438 (Oblizajek), which predicts HSU based on multiple low speed parameters such as radial run out (RRO), instantaneous rolling radius (IRR), and radial force variation (RFV) as obtained on low speed uniformity machines. Yet another example related to aspects of high speed uniformity is found in U.S. Pat. No. 6,065,331 (Fukasawa), which predicts higher order components of high speed uniformity based on low speed uniformity measurements. Low speed uniformity machines are well established and exist in all tire production lines. The above-referenced patents are incorporated herein by reference for all purposes. In light of these previous attempts to predict HSU parameters and the current marketplace focus on controlling HSU levels, it is desired to provide improved technology for characterizing tire uniformity at both high and low speeds.
There are many contributing factors to tire HSU, and thus one of the biggest challenges in effectively controlling tire uniformity lies in being able to properly identify such contributing factors in order to control corresponding levels of tire force variation and vehicle vibration. It has been determined in accordance with the present subject matter how both radial run out (such as created by geometrical non-uniformity or mass uneven distribution) and tire stiffness variations can cause both radial and tangential force variations. As such, it is desired in accordance with the presently disclosed technology to provide features for determining the contributions of radial and tangential force variations to tire non-uniformity at multiple harmonic levels.
Although known technology for characterizing tire uniformity and affecting associated aspects of tire manufacturing have been respectively developed, no design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology.